Rigging for the digging cable for a power shovel



March 20, 1956 R. A. FRITSCH RIGGING FOR THE DIGGING CABLE FOR A POWER SHOVEI..

2 Sheets-Sheet l Filed March 23, 1953 ATTORNEY March 20, 1956 R. A. FRITSCH Filed March 23,1953

RIGGING FOR THE DIGGING CABLE FOR A POWER SHOVEL 2 Sheets-Sheet 2 INVENTOR Wqll Ymfw AT TORNEY 1 RIGGING FOR THE DIGGIN G CALE FOR POWER vSHOVEL Robert A. Fritsch, Escanaba, Mich., assignor to Harnischfeger Corporation, Milwaukee, Wis., a corporation of i Wisconsin Application March z3, 1953, semiNo. 343,895 7 claims. (ci. 214-138) This' invention relates to power shovels and more specifically` resides in a shovel having a boom with a dipper stick dipper that extends outwardly from a machineryV platform, which platform carries a cable drum upon which is wound a'digging cable that extends outwardly along the boom to a cooperative engagement with the dipper stick for controlling movements thereof upon being drawn in or payed out from the drum, and wherein a` cable spool is mounted on the shovel to have wrapped thereabout a turn or more of the digging cable in its flight from the cable drum to the cooperative engagement with the dipper anddipper stick.

The digging cable of a power shovel that extends from a drum on the machinery platform outwardly along the boom for operation of the dipper and dipper stick usually departs from the drum at a slight angle to the normal n of the drum axis. This may be termed the fleet angle and if permitted to become substantial may detrimentally affect the action of the cable. Improper spooling on the drum may result and rubbing of adjacent turns -on the drum orbetween the cable and guiding sheaves on the boom may increase to cause excessive wear of the cable.

It is an object of this invention to guide the digging cable of a power shovel from its drum on themachinery platform at an angle with respect to the drum at which proper spooling on the drum will occur.

It` is lanother object of `this invention to provide in a power shovel for the drawingin or paying out of a digging cable'without the occurrence of excessive rubbing wear of the cable' as it winds upon or unwinds from the digging It is'another object of this invention to provide inV a power shovel for disposing the digging cable drum a substantial distance to the outboard side of cable guides on the boom while retaining a eet angle that remains within a desired range of Vsmall values.

It is another object of this invention to increase the effective length of the run of digging cable between the digging cable drum and the dipper and dipper stick without altering the position of the dipper and dipper` stick with respect to the cable drum. i i

cable drum or passes over cable guides along the boom.

powershovel shown in Fig. 1 showing thedgging cable with the dipper extended,

Fig. 3 is a fragmentary side view in elevation of the back`V acting power shovel shown in Fig. 1 with the boom ele.

vated and the dipper drawn in tight,and

Fig. 4 is a fragmentary top plan view of the back acting power shown in Fig. 1 showing the digging cable with bracket 16. The two brackets 15 support an auxiliary the dipper drawn in tight.

Referring now to the drawings, there is shown in Fig. p 1 a truck chassis 1 having a rear wheel assembly 2 over' which a circular roller track 3 is mounted. A roller engaging flange 4 extends about the track 3 to support a rotatable cab 5 having downwardly extending rollers 6 that rest upon and roll along the roller engaging flange 4.H A prime mover, not shown, is mounted in the housing 7 at the rear of the cab 5 and cable drum actuating machinery, also not shown, `is disposed within a housing 8 atihe forward end of the cab 5 to be driven by the prime mover. As is shown in Fig. 2, they housing 8 is centrallyV4 rotatably supported on mounted upon the cab 5 and both sides thereof are a number of cable receiving drums comprising a gantry cable drum 9, a boom cable drum l'and a digging cable drum 11. The drum 11 is tapered with the small diameter end Vat the outboard side of the drum.

Rising above the housing 7, is a main gantry frame 12 upon which are mounted a number of vertically disposed aligned sheaves 13`and a second set of sheaves 14, one of each of `which are shown in Figs. l and 3. At the forward end of the cab 5 are two widely spaced boom mounting brackets 15 and `an intermediary supplementary gantry 17 rising upwardly to the front of the main gantry 12 that carries at its upper end a large sheave 18 and two smaller sheaves 19 disposed on either side of the sheave 18.

A tiltable boom 20 extends outwardly from the cab 5 and its inner end is forked to provide a pair of boom feet 21. Each boom foot 21 has mounting brackets 22 pinned to the brackets 15 for the support of the boom 20. A horizontal shaft 23 is supported at its end between the supplementary bracket 16 and the pinned connection between the brackets"15 and 22 on the side of the cab 5 to which the digging cable drum 11 is disposed. Mounted boom sheaves and 31 are mounted on opposite sides It is another object of this invention to provide in `a power shovel for tilting of the boom while maintaining the length of the run of digging cable between the cable drum and the dipper and dipper stick substantially con stant in order to preserve dipper position with respect to the boom. p

These and other objects and advantages of this invention will appearV in the description to follow. In the description reference is made `to the accompanying drawings which form a part hereof and in which there is shown by way of 'illustration and not of limitation a specific form inwhich this invention may be embodied.

In the drawings: i

Fig. 1 is a side view in elevation with parts broken away ofa back acting power shovel in which this invention is embodied showing the dipper in an extended position,

of the boom 20, and on the underside of the boom 20` is a dipper sheave stop 32 which is disposed to engage the sheave 29 upon pivoting the dipper stick 25 tightly under the boom 20, as is shown in Fig. 3.

To retain'the auxiliary gantry `17 in elevated position a gantry cable 33 leads from the gantry cable drum 9 upwardly toward a sheave 13 at the top of `the gantry 12 and passes over thesheave 13 to a sheave 19 on the auxiliary gantry 17. The cable 33 then passes about the sheave 19 and extends rearwardly to the sheaves 14 on the gantry 12. From the sheaves 14 the cable 33 again runs forwardly to the second sheave 19 and hence about the sheave 19 and rearwardly to pass over the second sheave 13 to an anchorage 34 on the rear of the gantry 12. l A boom'hoist cable 35 is wound upon the hoist cable drum 10 and leads from'the drum 10 upwardly and about a connection with the gantry 17.

The third control cable employed is the digging cable Patented Mar. y2o, 195e- 36, which is wound about the digging cable drum 11 with its dead end at the small diameter outboard side of the drum 11. From the drum 11 the cable 36 leads forwardly tothe cable spool 24 and isV wrapped twice thereabout as shown in Figs. 2 and 4. From the spool 24 the cable 36 extends to the boom sheave 30 that is disposed forward of' the spool 24 and hence to thev dipper sheave 29. Cable 36 passes about the sheave 29 to return over the boom sheave 31 and fasten to an anchorage 37 ixed on the topside of the boom 20.

Digging with a back acting shovel, as shown in the drawings, is accomplished by coordinating the movements ofthe hoist and digging cables 34, 36. The digging cable 32 is used primarily to control the position of the dipper stick 25 and dipper 28 with respect to the boom 20 and the hoist' cable 35 primarily controls the elevation of the boom 20. To effectively employ the apparatus dual manipulation of these control cables is however necessary. Upon completion of a digging stroke, in which the cable 36 is drawn in upon the drum, 11 and the dipper 28 is moved in close under the boom 20, it is of advantage to retain the digging cable 36 taut and the length of run of the cable 36 between the drum 11 and the sheave 29 substantially constant as the boom 20 is raised to a position like that of Fig. 3. Premature dumping will then be precluded. Through the employment of this invention the cable 36 is prevented from slacking and dipper position with respect to the boom is maintained by disposing the cable spool 24 concentrically with the pivot of the boom feet 21 and passing the cable 36 thereabout. As the boom is pivoted the digging cable run from the drum 11 to the dipper will not materially change.

The size ofthe tleet angle changes as the cable 36 is wound upon or payed out from the drum 11, since the point of departure ofthe cable 36 from the drum 11 will move along the drum axis. To avoid excessive abrasive rubbing of the cable at the sheave 30 or between adjacent turns on the drum 11 and to provide for proper spooling upon the drum 11 the fleet angle should be small and permissive maximum values are usually of the order of three degrees. To this end, one or more turns about the spool 24 increases the effective length of cable run between the drum 11 and the sheave 30 to reduce the fleet angle and bring it within permissible limits. To further induce proper spooling upon the drum 11 it is tapered, as hereinbefore noted. With the selection of proper dimensions the turns on the drum 11 will form snugly against one another.

With the dipper 28 extended there will be a minimum of turns on the drum 1l, as shown in Fig. 2. In passing about the spool 24 the adjacent turns of cable are spaced 5 one from the other. There will be no rubbing contact between turns unless an excessive number are wound about the spool 24. ln drawing the cable 36 on to the drum 11 the taper will cause the turns to form snugly against one another and with the dipper 28 fully retracted under the boom 22, so that the sheave 29 is brought up tight against the stop 32 the cable 36 will assume the position on the drum 11 and spool 24 as shown in Fig. 4. The eet angle is now at a minimum and the separation between turns on the spool 24 is small. The entire section of cable on the drum 11 is to the outboard of the guiding sheave 30, so that the eet angle at all times falls to one side of the normal of the drum axis.

To wind the cable 36 about the drum 11 in snugly adjacent turns the taper for the drum may be chosen with particular reference to the maximum fleet angle. A selection of a taper angle slightly greater than the maximum fleet angle will cause the cable to lead onto the drum 1 1 with a tendency to move outboard against the adjacent turn. Thus, improper spooling wherein the cable Wound drift to the inside end ofthe drum 11 is elim inated. Consequently, as the cable leaves or unwraps from the drum 11 there will be little, if any, deleterious rubbing, since the cable extends obliquely away from the wound turns.

l claim:

l. In a power shovel the combination comprising a machinery platform; a digging cable drum mounted on said platform rotatable about an axis and adapted to have cable wound thereon and led therefrom, a boom assembly including a boom joined at one end to said platform and extending outwardlytherefrom, a dipper stick pivotally mounted on said boom, a dipper mounted on said dipper stick, and digging cable guide means adapted to guide a cable for controlling said dipper stick and dipper offset with respect to the drum axis toy one side of where cable may be led from the drum; a cable spool intermediary said drum and said cable guide means disposed with respect to the drum axis between said guide means and where cable may be led from said drum; and a digging cable wound on said digging cable drum extending therefrom toward said spool and encircling said spool from which it extends to said' cable guide means to bev received thereby, said cable extendingl from both said drum and said spool and traveling about said spool with a component of direction, with respect to the drum axis toward said guide means.

2. In a power shovel the combination comprising a machinery platform; a digging cable drum mounted on said platform adapted to receive turns of cable traveling axially along the same and to have cable wound and unwound therefrom', a boom assembly including a boom joined at one end to said platform and extending outwardly therefrom, a dipper stick pivotally mounted on said. boom, a dipper mounted on said dipper stick, and digging cable guide means adapted to guide a cable for controlling said dipper stick and dipper offset to one sideof the cable receiving portions of said drum; a cable spool of a length extending axially with respect to said drum to permit turns of cable wound thereabout to shift position along the length of the same; and a digging cable wound on said digging cable drum extending therefrom toward said spool and circling about said spool from which it extends to said cable guide means to be received thereby, said cable being shifted along said spool as the point of departure at which the cable leaves said drum is shifted with winding and unwinding from the drum, and the cable extending from both the drum and the spool with fleet angles constantly bearing to the side of the drum to which said guide means is offset.

3. In a power shovel the combination comprising a machinery platform; a boom assembly including a boom with boom feet at one end pivotally connected to said platform and extending outwardly from said platform., a dipper stick pivotally mounted on said boom at a point remote from said boom feet, a dipper mounted on said dipper stick, and digging cable guide means adapted to guide a cable extending outwardly along said boom; a digging cable drum rotatable about an axis mounted on said platform adapted to receive several turns of cable traveling axially along said drum that when wound thereon are disposed outboard of said guide means; a cable spool mounted concentric with the pivot of said boom feet; and a digging cable wound on said drum from the outboard side inwardly extending therefrom toward said spool and encircling said spool in an outboard to inboard direction from which it extends to said cable guide means to be received thereby, whereby said cable shifts along said spool as winding and unwinding from said drum takes place to maintain substantially equal eet angles for the cable from both the drum and the spool.

4. ln a power shovel the combination comprising a machinery platform; a boom assembly including a boom pivotally joined at one end to said platform and extending outwardly therefrom, a dipper stick pivotally mounted on said boom, a dipper mounted on said dipper stick, and

digging cable guidefmeans adaptedto guide a cable for controlling said dipper stick and dipper; a digging cable drum mounted on said platform outboard of said cable guide means; a cable spool of a length that a turn of cable wound thereabout may be shifted in inboard and outboard directions along the spool as such cable is passed about the same mounted concentric with the pivot of said boom and aligned between said drum and said cable guide means; and a digging cable on said digging cable drum with a dead end toward the outboard end of said drum and wound thereabout in turns traveling inwardly along said drum, said cable extending from said drum toward and encircling said spool with an inboard component of direction from which it extends with a continued inboard component of direction to said cable guide means to be received thereby, whereby said cable moves inboard and outboard along said spool as cable is wound and unwound respectively from said drum.

5. In a power shovel the combination comprising a machinery platform; a boom assembly including a boom pivotally joined at one end to said platform and extending outwardly therefrom, a dipper stick pivotally mounted on said boom, a dipper mounted on said dipper stick, and digging cable guide means adapted to guide cable for controlling said dipper stick and dipper; a digging cable drum mounted on said platform outboard of said cable guide means having a taper with decreasing diameter in outboard direction; a cable spool of a length to receive spaced turns of cable that may be shifted along the spool as such cable is passed about the same mounted concentric with the pivot of said boom aligned between said drum and said cable guide means; and a digging cable on said digging cable drum with a dead end toward the outboard end of said drum and wound thereabout in turns of increasing diameter inwardly along said drum, said cable extending toward said spool with an inboard component of direction and encircling said spool with turns spaced from one another from which it extends with anv inboard component of direction to said cable guide means to be received thereby, whereby said cable moves along said spool as winding and unwinding occurs on said drum to provide fleet angles for cable leading from both the dnnn and the spool smaller than that of a cable led directly from said drum to said guide means.

6. A claim in accordance with claim 5 wherein the angle of taper of said drum is greater than the maximum iieet angle at which cable leaves said drum.

7. In a power shovel the combination comprising a machinery platform, a boom joined at one end to said platform and extending outwardly therefrom, a dipper stick pivotally mounted on said boom, a dipper mounted on said dipper stick, a digging cable guiding sheave on said boom, a digging cable drum on said platform disposed outboard of said sheave, a cable spool of a length to permit a spiral turn of cable wrapped thereon to travel along said spool a substantial distance as such cable is passed about the same aligned between said drum and said sheave, and a digging cable wound on said digging cable drum extending therefrom toward said spool and encircling said spool from which it extends to pass over said sheave and lead to a cooperative engagement with said dipper and dipper stick, said cable constantly passing between said drum and spool, about said spool and between said spool and sheave with an inboard component of direction as cable is wound on and unwound from said drum.

References Cited in the file of this patent UNITED STATES PATENTS 1,843,793 Wagner Feb. 2, 1932 2,022,808 Kerr Dec. 3, 1935 2,377,495 Hofmeister June 5, 1945 2,416,826 Gallaher Mar. 4, 1947 2,498,000 McLean Feb. 21, 1,950 

